import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory
import os

import launch_ros.parameter_descriptions

def generate_launch_description():
    # 获取urdf的路劲，即为model的路径
    urdf_package_path = get_package_share_directory('fishbot_description')
    default_urdf_path = os.path.join(urdf_package_path,'urdf','first_robot.urdf')
    default_rviz_config_path = os.path.join(urdf_package_path,'config','display_robot_model.rviz')
    # 获取完model路径后，方便后续参数直接替换新的模型，这里改为可传入参数
    action_declare_arg_mode_path = launch.actions.DeclareLaunchArgument(
        name='model',default_value=str(default_urdf_path),description='加载的模型文件路径'
    )
    # 使用命令来替换结果的内容。即用cat +模型的路径，即cat urdf文件的路径，获取udrf的内容
    substitutions_command_result = launch.substitutions.Command(['xacro ',launch.substitutions.LaunchConfiguration('model')])
    # 将上面获取的udrf的内容作为参数值
    robot_description_value = launch_ros.parameter_descriptions.ParameterValue(substitutions_command_result,value_type=str)
    # 调用安装的robot_state_publisher命令，启动命令传入参数
    action_robot_state_publisher = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description':robot_description_value}]
    )

    action_joint_state_publisher = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher'
    )

    action_rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        arguments=['-d',default_rviz_config_path]
    )

    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        action_robot_state_publisher,
        action_joint_state_publisher,
        action_rviz_node
    ])